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- Posts: 15
- Joined: Thu Apr 09, 2015 11:52 am
Hello all,
I recently had reset my autosampler to factory settings, changing the puncture depth and my needle broke upon injection. I'm now having injection problems which I hope to fix by inquiring if I made a mistake upon replacing the needle my self.
I was hoping someone had one of the 2.4 uL replacement syringes handy and could provide me with some measurements. Mainly, the total length and the distance from the tip to the rubber piece where it bends for the holder.
I used a micrometer to measure the OD as 280 um and based on a length estimate of our old needle ( which I have no idea if it was Dionex/Thermo's or silica a previous lab member replaced ) of ~ 28 cm the ID should be 100 um.
Upon breaking and my own measurements, I replaced the needle with ~ 28 cm of 300 OD 100 ID um silica. I changed the puncture setting to the max of 11 mm, used the Chromeleon command to puncture our sample vials, fed the silica down to the bottom, and after hitting the bottom pulled up a little. Much like packing fused silica in the high pressure bomb.
My Flush 1 and overfill should be sufficient for the needle volume and loop. A difference measurement of a sample vial with water showed that the needle did pick up some liquid on "inject" and the needle does release liquid into the wash port when I use that command. Upon injection of sample I'm not seeing the expected results. I'm looking into my sample prep, but that hasn't changed and I'm not even seeing the unretained junk in the chromatogram.
I'm considering the draw velocity but I don't want to start playing with that until I'm positive the problem isn't before that.
( Wow that was more than I was planning to write. )
Much obliged.
I recently had reset my autosampler to factory settings, changing the puncture depth and my needle broke upon injection. I'm now having injection problems which I hope to fix by inquiring if I made a mistake upon replacing the needle my self.
I was hoping someone had one of the 2.4 uL replacement syringes handy and could provide me with some measurements. Mainly, the total length and the distance from the tip to the rubber piece where it bends for the holder.
I used a micrometer to measure the OD as 280 um and based on a length estimate of our old needle ( which I have no idea if it was Dionex/Thermo's or silica a previous lab member replaced ) of ~ 28 cm the ID should be 100 um.
Upon breaking and my own measurements, I replaced the needle with ~ 28 cm of 300 OD 100 ID um silica. I changed the puncture setting to the max of 11 mm, used the Chromeleon command to puncture our sample vials, fed the silica down to the bottom, and after hitting the bottom pulled up a little. Much like packing fused silica in the high pressure bomb.
My Flush 1 and overfill should be sufficient for the needle volume and loop. A difference measurement of a sample vial with water showed that the needle did pick up some liquid on "inject" and the needle does release liquid into the wash port when I use that command. Upon injection of sample I'm not seeing the expected results. I'm looking into my sample prep, but that hasn't changed and I'm not even seeing the unretained junk in the chromatogram.
I'm considering the draw velocity but I don't want to start playing with that until I'm positive the problem isn't before that.
( Wow that was more than I was planning to write. )
Much obliged.
